1. Field of the Invention
The present invention relates to a collision avoidance method, a control device, and a program, and specifically relates to a collision avoidance method, a control device, and a program that avoid collision of a robot arm.
2. Description of Related Art
A method of operating a robot arm including a plurality of joints in real time by controlling an operation of the robot arm includes, for example, a master slave method. In the master slave method, a master device (control device) specifies a control value and a slave device (robot arm) operates according to the control value that has been specified. When a hand position of the robot arm is specified as the control value, a joint angle of each joint is calculated using an inverse kinematics calculation.
There is an obstacle such as a torso of a robot around the robot. Therefore, when the robot arm is controlled by specifying the hand position of the robot arm, it is required to not only calculate the joint angle of each joint but also calculate a solution in which the robot arm does not collide against the obstacle such as the torso (collision avoidance solution). When the robot arm is operated in real time, the calculation of the joint angle and the calculation of the collision avoidance solution stated above need to be performed in real time.
Regarding the above technique, Japanese Unexamined Patent Application Publication No. 2011-093015 discloses a control device of a hand-eye bin-picking robot to prevent collision of a hand part of a robot arm with a surrounding environment in consideration of the existence of a hand-eye sensor. The control device disclosed in Japanese Unexamined Patent Application Publication No. 2011-093015 includes table storage means for storing a collision pattern table, moving destination collision determination means for determining whether the hand-eye sensor collides against the robot arm, and posture re-determination means.
The collision pattern table defines combination patterns of the rotation angle in each free axis of the robot arm in which the hand-eye sensor collides against the robot arm. Further, the moving destination collision determination means determines whether the hand-eye sensor collides against the robot arm based on a comparison between the combination patterns of the rotation angles in each of the free axes and the combination patterns defined in the collision pattern table when the robot arm is driven in such a way that an end effector has a posture determined in the position of a workpiece. When it is determined that the hand-eye sensor collides against the robot arm, the posture re-determination means determines a new posture of the end effector suitable for the picking of the workpiece.